1. Field of the Invention
The present invention relates to a technical field of the lens driving apparatus for driving an objective lens.
2. Related Art
In a conventional technique, a lens driving apparatus which includes a suspension base, a bobbin which is movably provided with respect to the suspension base, an objective lens retained by the bobbin, and a suspension wire which elastically connects the suspension base to the bobbin is disclosed in Japanese Unexamined Patent Publication No. JP-A-10-269600.
However, the above conventional lens driving apparatus has a problem of a so-called rolling phenomenon in which a lens holder (bobbin) rotates in a jitter direction (hereinafter referred to as a rolling direction) by mismatch of the center of gravity and a line of action of driving force when the lens holder is driven in the tracking direction.
Ordinarily, because the resonance frequency of the conventional lens driving apparatus in the rolling direction exists in a range of several dozen of Hz to one hundred and several dozen of Hz, there may be a case where the resonance frequency in the rolling direction matches the rotary frequency (utmost about 170 Hz) of an optical disk. In this case.
In this case, when the optical disk is driven to rotate, there is a problem that a phenomenon of rolling is induced and a coma aberration is produced by losing a symmetry of a light beam which passes through the objective lens, and a signal level for recording and reproducing is turned down.